This invention relates to a fuel filter, fuel vapor separator, and flow check or roll-over valve in the fuel supply line between the carburetor and an engine driven fuel pump for an automobile engine and has for a specific object the provision of improved flow check means in the fuel supply line to prevent fuel leakage from the fuel tank in the event of an accident, as for example where the automobile is rolled over or tilted to such an angle that fuel would otherwise flow by gravity through the fuel line from the tank.
Invariably in consequence of such an accident, the engine stalls. Another object therefore is to provide a flow check or roll-over valve as above comprising a poppet type valve which is normally closed to prevent fuel leakage from the fuel tank when the engine is not operating, but which opens when subjected to comparatively high output pressure from the fuel pump when the engine is operating, and which thereafter remains open in response to comparatively low fuel pump pressure. Accordingly as soon as the valve opens, the pump operates normally and efficiently against comparatively small back pressure, conserving power, and minimizing wear and the necessity for costly high pressure components. Also minimized is the possibility of vapor lock and consequent inefficient pump operation which might otherwise occur during hot operating conditions if the pump were required to pump against a greater output pressure.
The fuel supply line is ordinarily subject to heat from the road and the engine exhaust system. Vapor formation which interfers with proper operation of the fuel pump and fuel metering at the carburetor tends to increase as the liquid fuel flows from the tank to the carburetor. Where fuel vapor formation is a problem, it is customary to separate the vapor from the fuel supply line adjacent and upstream of the carburetor to enhance fuel metering and also to return the vapor and excess fuel discharged from the fuel pump to the fuel tank via a restricted return line, thereby to minimize vapor formation and vapor lock in the pump by assuring a continuous flow of comparatively fresh cool low pressure liquid fuel through the pump.
Another object of the invention is to provide a roll-over valve of the above character which is cooperable with a vapor separator and a low resistance fuel filter combination comprising a restricted vapor return line to the fuel tank connected with the fuel supply line at a location between the fuel pump and both the filter and roll-over valve, whereby fuel vapor if any is returned to the fuel tank along with a portion of the liquid fuel output from the pump. Any vapor that does form in the pump is discharged along with liquid fuel by virtue of the low back pressure on the pump effected by the comparatively low resistance of the filter and roll-over valve and the restriction in the vapor return line, which restriction is predetermined to force fuel through the filter and roll-over valve to the carburetor.
Another object is to provide the combination of elements as aforesaid wherein many of the components may be readily manufactured economically within the required production tolerances from sheet metal stampings, and wherein the filter is located upstream of the check valve to protect the latter's closely interfitting parts from solid particulates or other dirt in the fuel and interfering with closing of the valve when the pump is not operating, thereby to assure positive and reliable operation of the valve in preventing fuel leakage in the event of a vehicle roll-over.
Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.